Immunohistochemical study of pleomorphic adenomas in salivary gland

Immunohistochemical study was performed on three cases of pleomorphic adenomas of the salivary gland to investigate the origin of neoplastic epithelium and especially about the presence of myoepithelial components. We analyzed the distribution of immunohistochemical staining in the inner cuboidal tubular epithelium, outer flattened tubular epithelium, solid nest of epithelium, and epithelial cells of myxoid stroma ; using antiS-100 protein antibody with its α and β subunits’ anticarcinoembryonic antigen antibody, and cytokeratin antibodies (MA-902, MA-903). The epithelial cells of myxoid stroma were positively stained only to the antiS-100 protein antibody. The inner cuboidal tubular epithelium was positively stained to all four types of antibodies. The outer flattened tubular epithelium and the solid nests were positively stained only to two types of antibodies, MA-903 and antiS-100 protein antibody which were known to be reactive to myoepithelial components. Our study suggested that the myoepithelial components may be involved in the origin of salivary gland pleomorphic adenoma, however, multidirectional differentiation of the tumor should be considered together.